Prior to this invention, processes for degasifying coal have been limited by the need for extensive piping systems from an underground mine face to the surface. For example, Ranney, U.S. Pat. No. 1,867,758, shows a process for degasifying coal which requires piping and possible pumping to convey gas to the surface from horizontal and vertical bore holes in a coal mine.
Schneiders, U.S. Pat. No. 1,418,097, shows a process for pumping oil and gas to the surface of a mine from horizontal or slanting bore holes, and Byers, U.S. Pat. No. 12,928, shows a method for collecting only dust and solid particles by a gravity settling process and exhausting the gases which are also collected.
A study contract performed by Arthur D. Little, Inc., Cambridge, Massachusetts, for the U.S. Bureau of Mines, "Economic Feasibility of Recovering and Utilizing Methane Emitted from Coal," (Apr. 15, 1975) reports on methods for drilling bore holes in a mine for draining methane and discusses piping the recovered methane to the surface.
Bureau of Mines publication No. RI-8173, entitled "Degasification and Production of Natural Gas From an Air Shaft in the Pittsburgh Coal Bed," by Fields et al (1976), indicates the problems associated with the use of underground pipelines in mines to transport methane out of the mine, e.g., leakage caused by improper installation or alignment of the pipeline. The Bureau of Mines report discloses the use of a water gas separator having a receiver for the water and piping the separated gas to the surface.
An article appearing in the periodical A.G.A. Monthly entitled, "Degasification of Coal Beds--A commercial Source of Pipeline Gas" (May, 1976) by M. Deul indicates that productivity from "gob" degasification holes does not justify a permanent surface installation, but that "the use of portable gas turbines or gas liquefaction concentrators to conserve the gas is worth investigating." (A.G.A. Monthly/May, 1976 at page 8.)
It is an object of this invention to provide a method and means for recovering and removing methane and minor other portions of hydrocarbon gases at or near the coal face in a subterranean mine before the coal is mined and for eliminating the piping and pumping requirements of conventional degasifying systems.
A further object of this invention is to provide a method and apparatus for reducing hazardous and noxious mine gases in the mine, thereby eliminating the need for piping and pumping larger volumes of ventilation air to dilute these dangerous gases at the subterranean coal face.